Learning Perl, 4th Edition Notes 0x6

Learning Perl, 4th Edition Notes 0x6 by DaNmarner * The support for regular expressions (patterns) in perl allows fast, flexible and reliable string handling. * Some considered Regular Expression, whose function is to judge whether a string matches the template it stands for or not, a simple programming language. * Pattern is match is generally being used to return a true or false value. It's almost always found in if or while structure. * Some characters have special meanings in regular expression. These characters are named metacharacter. When matching them as a literal character, put backslash before them. * Metacharacter dot (.) matches any single character except a new line. Backslash itself is a metacharacter, too. * Use quantifiers when the quantitiy of the preceding item needs to be specified in a regular expression. A question mark (?) means the preceding item occurs 0 or 1 time. The plus (+) quantifier means 1 or more, while the star (*) means both. * Parentheses are the metacharacters that group the stuff. * The vertical bar (|) means "or". * A list of possible characters inside square brackers ([]) is called a character class. Which matches any single characters from within the class. * Hyphen (-) specifiys a range of characters in character classes. * A caret (^) at the start of a character class negates it. * Several character class shortcuts: d leaded by a backslash stands for [0-9], while w for [A-Za-z0-9_] and s for [\f\t\n\r ]. To negate them, use capital letters instead.